Aboard ships, in nuclear and water treatment plants, in the treatment of wastewater effluents, and the like, it is often necessary that valves of varying sizes be continuously opened, closed, or controlled. Heretofore, such valves were manually or automatically operated, or opened or closed completely or partially from a remote control point. Large industrial valves, and shipboard valves, for example, are oftentimes controlled by a handwheel which controls the opening and closing of the remotely disposed or inaccessible valves by means of rotatable flexible shafts communicating therebetween. Considerable torque was usually required to rotate the handwheel. Further, the flexible shaft was proportionately large, heavy, and expensive.
As a typical example, a 3/4" flexible shaft connected an inaccessible valve and the handwheel in a certain industrial plant. The flexible shaft was made by the assignee of the present invention and weighed approximately 114 lbs./100 feet. By substituting a 1/4" flexible shaft for the 3/4" shaft, in accordance with one aspect of the present invention, a savings of over 100 lbs./100 feet of shaft was realized as well as a very considerable savings in cost.
In the present invention, a handwheel may rotate a driver pulley which rotates a smaller driven pulley by means of a timing belt interconnecting the two. The spindle of the driven pulley rotates a flexible shaft which, in turn, may be connected to a step-down pulley-belt mechanism associated with the valve to be controlled. For smaller type valves, the pulley-belt arrangement at the handwheel may be eliminated.
In lieu of a step-down pulley-belt arrangement at the valve end, or in conjunction therewith, gearing structure, such as spiral gears, for example, comprising a pinion and a driven gear may be employed. The output spindle of the driven gear will cause the valve stem to be turned as desired, or, the output spindle may be connected to another step-down pulley-belt arrangement. In the former, the driven gear may be stepped down, i.e., the driven spiral gear will be provided with more spiral teeth than the pinion, thus reducing the torque necessary to turn the handwheel. A plurality of remotely disposed satellite valves may be serially connected for simultaneous opening or closing by a single handwheel and yet the flexible shafting connected between successive valves will oftentimes be lighter in weight and less costly than a single flexible shaft connected between a handwheel and a single valve.
To accommodate for differences in the number of turns required to open or close the various valves in the system, the invention incorporates torque-limiting devices to provide slippage of components to reduce the occurrence of any malfunctioning or overtorquing.